Manufacture of cast iron



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Patented Nov. 1, 1938 PATENT OFFICE 2,134,905 I MANUFAc'rUan'or cAs'r mou James Warwick Bamptylde, Birmingham, England, assignor to British & Dominions Fer-alloy Limited, London, England No Drawing. Application January 11, 1938, Se-

rial No. 184,486. In Great Britain January 30,

This invention has forits object to provide an improved method of manufacturing cast iron having as its main constituents ordinary cast iron and from 0.5 to 9% of aluminium, with or without the addition of from 0.1 to 3.5% of chromium. The invention further comprises the method of manufacture, wherein the molten cast iron (with or Without chromium) is poured into a heated ladle containing the requisite amount 01 molten aluminium, and a gas having as its chief constituents carbon and chlorine is bubbled through the metals for the purpose of removing aluminium oxide.

In one, manner of carrying the invention into effect I employ a heated ladle or crucible into which is placed a quantity of molten aluminium. In this ladle or crucible is then poured a molten quantity of ordinary cast iron. The amount of aluminium used is such that when mixed with the iron it will give-an alloy containing not more than 9% of aluminium. The amount of alumin ium may be varied, but it is never less than 0.5%..

By ordinary cast iron I mean cast iron containing any of the amounts cl carbon normally found in cast iron, together with any other normal ingredients such as silicon; the maximum amount of carbon should besuch that in the tinished alloy it shall not exceed 3.1% when the silicon content does not exceed 1.0%, but if the sill con content exceeds this amount then the mam mum amount of. carbon should be suitably less than 3.1% to minimize the risk of occurrence of kish in the finished alloy.

After the cast iron has been added to the aluminium, a cleansing gas is applied for the removal of aluminium oxide. .Thls gas has as its chief constituents carbon and chlorine, and it maybe obtained from such substances as trichlorethylene, carbon tetrachloride, or chlorinated pitch, the latter being usually the more convenient. a quantity of chlorinated pitch is placed in a tube which is closed at one end. The charged tube is inverted and. its open end is thrust into the lowerpart of the molten mass. Under the action of the heat of the metal the chlorinated pitch is gasslfled, and the gas is allowed to bubble through the molten mass for producing the effect above-mentioned. By means of the gases the aluminium oxide is converted into aluminium chloride which is volatile at the temperature oi. the molten mass.

2 Claims. (01.. Til-127i After treatment with the cleansing gases, the molten mass is poured into moulds.

By this invention 1 am able to provide cast iron articles which have good heat resisting proper ties, are physically strong, and are capable of it being readily machined.

A good example of a grey cast'iron alloy made in accordance with this invention has in addition to iron the following approximate composition: aluminium 7.5%, silicon 1.0%, total carbon 2.7%. Such an iron is heat resisting and machineable. and not only has it good mechanism strength at v ordinary temperatures but its strength at teniperatures as high as 500 centigrade is not only equal to that at ordinary temperatures but issubstan'tially higher. Beyond that temperature the strength diminishes in a manner common to most cast irons. I find, moreover, that the mechanical strength can be increased, without detracting frlirn the essential property oi resistance to oxidation at high temperatures, by the addition of chromium in amounts ranging from ll.l% to A good example is one having the particlelar composition above specified, with about 0.'l'5% of chromium. The chromium is added to the molten iron belore the latter is added to the aluminium.

, Having thus described my invention what I claim as new and desire to secure by Letters Patent is:--

l. A process for making a cast iron alloy having as its constituenm ordinary cast iron and from 0.5% to 9% of aluminium, consisting in pouring the requisite amount of molten cast iron into a heated receptacle containing the requisite amount of molten aluminium. and bubbling through the metals 9. gas having as its chief constituents carbon and chlorine for the purpose of removing aluminium oxide.

2. A process for making a cast iron alloy having as its constituents ordinary cast iron, from 0.5% to 9% of aluminium, and from 0.1% to 3.5% oi chromium, consisting in adding the requisite amount of chromium to the requisite amount of molten cast iron, pouring the molten cast iron containing the chromium into a heated receptacle containing the requisite amount of molten 1111- ininium, and bubbling through the metals a gas having as its chief constituents carbon and 01110- I rine for the purpose of removing aluminium v oxide.

JAMES WARWICK BAMPI 'YIDR. 

